The present invention relates to a method for enhancing the conversion of carbonous materials such as coal, oil shale, and peat, to liquids, by use of specific type hydrogen donor materials under critical processing conditions.
Coal, once the leading source of energy in the United States, is beginning to play a more important role in the nation's energy future. The primary reason for the growing importance of coal is the rapid depletion of known petroleum and natural gas reserves. These known reserves are being depleted at a rate considerably faster than the rate of discovering new reserves. As the era of petroleum growth draws to a close, the world's energy mix will have to change. Transition energy sources will be needed as a bridge between petroleum and the potentially unlimited energy sources of the future; such sources being, for example, solar power and nuclear fusion. Owing to their great abundance, coal and oil shale, are perceived as the keystones of such a bridge. Consequently, much work is presently in progress to provide economical ways of converting these resources to valuable liquids and gases. Coal liquefaction processes in which coal, with or without a diluent, is subjected to elevated temperatures and pressures to convert solid coal to normally liquid hydrocarbonaceous products, are well known.
Because the ratio of hydrogen to carbon in coal derived liquids and gases is higher than coal itself, gases, much emphasis has been put on more efficient uses of hydrogen in liquefaction processes. In order to use hydrogen more efficiently, processes have been developed wherein a source of hydrogen is an organic compound, usually a solvent, which is capable of donating hydrogen to radicals formed during the decomposition of coal. Although such processes teach the conversion of coal to liquids and gases under various conditions, and with various yields, none are able to achieve relatively high conversion to liquids under low pressure conditions.